In the related art, a fact that exposure to ultraviolet rays exerts a negative influence on the eye is regarded as an issue. Furthermore, in recent years, a fact that blue light, which is included in natural light or in light emitted from liquid crystal displays of office machines, displays of portable devices such as smartphones or cellular phones, and the like, exerts an influence on the eye and makes the eye feel fatigue or pain has become an issue. Therefore, it is required to reduce exposure of the eye to ultraviolet rays and blue light having a relatively short wavelength of about 420 nm.
Non-Patent Document 1 describes the influence of short-wavelength blue light of about 420 nm on the eye.
In this document, damage of retinal neuronal cells (rat R28 retinal neuronal culture cells) irradiated with blue LED lights having different peak wavelengths of 411 nm and 470 nm was verified. As a result, it was found that while irradiation (4.5 W/m2) of blue light having a peak wavelength at 411 nm caused death of the retinal neuronal cells within 24 hours, blue light having a peak wavelength at 470 nm caused no change in the cells even if the cells were irradiated with this light at the same dose. This result shows that in order to prevent eye injury, it is important to inhibit exposure of the eye to light having a wavelength of 400 nm to 420 nm.
Moreover, it is considered that if irradiated with blue light for a long time, the eye may suffer from fatigue or stress, and this may lead to age-related macular degeneration.